70-200 III w/1.4 III vs 300f4?

I'm considering getting rid of my older 300 f4 LIS and getting a 1.4 converter lll for the 70-200. It would end up being a 280mm f4 lens so close to the bare 300. Question is how would the image quality compare between the two lenses? The 300 is an old design so I'm guessing technology would tend to even them out. Anyone use both of these that they can comment on? Thanks.

The 300f4 will be slightly sharper.

https://www.the-digital-picture.com …omp=0&FLIComp=4​&APIComp=1

You may want to consider the 70-300L. Very underrated lens that is fairly compact. I had one years ago and it’s one of the few lenses I regret selling.

I have the 70-200 II and a 300 f4. I can't give you a direct answer. I really like my 70-200II does an amazing job at indoor sports. I don't love the lens with the 1.4 TC. I really like my 300 f4. I find the lens crazy sharp. I do find the range limiting for different types of shoots. I do find it great for outdoor sports and some wildlife.